Constrained fermionic system and its equivalence with the free parafermionic theory and nonlinear sigma model

We construct the parafermionic (of orderq) representation of the Kac-Moody and Virasoro algebra and compare it with a constrained fermionic system. We find that the central charge of the Virasoro algebra of the constrained fermionic system depends on the regularization scheme. Using the path integral method, we demonstrate this dependence for theq=2 case and find that it can have the same central charge as the free parafermionic theory or the non-linear sigma model depending on the regularization scheme. We point out some ambiguity in the quantization of the constrained system in Hamiltonian formulation.     

Non‐Alkaloidal Constituents from the Stem of Ficus Septica

Seven triterpenes, two lignans, and twelve other known compounds were isolated from the non‐alkaloidal fractions of the stem of Ficus septica Among these triterpenoids, a rare triterpene skeleton derivative, 13,27‐cycloursan‐3β‐ylacetate was isolated from natural sources for the first time. All the structures of these compounds were elucidated by spectroscopic methods.     

Improving the dispersion and interfaces in polymer‐carbon nanotube nanocomposites by sample preparation choice

Polymer nanocomposites composed of poly(styrene‐ran‐vinyl phenol) (PSVPh) copolymers and 5 wt % multi‐walled carbon nanotubes (MWNTs) were prepared by three different methods, including melt‐mixing and precipitation. The MWNTs were either oxidized to incorporate oxygenated defects or utilized as received. The mechanical properties of the nanocomposites were measured by dynamic mechanical analysis (DMA), and the extent of intermolecular hydrogen bonding between MWNTs and PSVPh was quantified by infrared (IR). Our DMA results suggest that melt‐mixing leads to more stable morphologies of the final nanocomposites than precipitation. Additionally, the IR analysis of the nanocomposites indicates melt‐mixing can result in the formation of more intermolecular hydrogen bonding between the MWNTs and PSVPh than precipitation, and thus suggests that melt‐mixing leads to more reproducible mechanical properties than precipitation. Our DMA and IR results may provide guidelines to realize the desired morphologies and to improve the properties of polymer carbon nanotube nanocomposites by optimizing intermolecular interactions between MWNTs and polymers using processing. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 1747–1759, 2008     

Formal Synthesis of (±)-Mitsugashiwalactone and (±)-Isodihydronepetalactone from Norborn-5-en-2-one Involving Shapiro Reaction

A formal synthesis of (±)-mitsugashiwalactone ( 1 ) and (±)-isodihydro nepetalactone ( 2 ) was accomplished. Baeyer-Villiger lactonization of ketone 9 followed by acidic treatment led to the rearranged lactone 8 , which underwent a series of functional group transformations to give cyclopentanone derivatives 19 and 20 . Shapiro reaction on 21 and 22 in the presence of excess dry ice gave lactones 5 and 6 . Lactones 5 and 6 previously have been converted to mitsugashiwalactone ( 1 ) and isodihydronepetalactone ( 2 ), respectively.     

Preparation of NiZn-ferrite nanofibers by electrospinning for DNA separation

We present the synthesis, magnetic and UV spectrometry of NiZn-ferrite nanofiber. The single phase of spinel ferrite was obtained at 600 °C. The NiZn-ferrite fibers fabricated by an electrospinning process were formed as a polygonal grain growth with firing temperature in fiber matrix. It appeared that the saturation magnetization (M_S) of NiZn-ferrite nanofiber was dependent on Ni/Zn molar ratio which is similar to that of the inverse spinel ferrites. The NiZn-ferrite fibers showed good DNA adsorption efficiency that can be modified and utilized for DNA separation with magnetic nanofiber as a novel material in clinical applications.     

Flexible nanocrystalline‐titania/polyimide hybrids with high refractive index and excellent thermal dimensional stability

In this study, a novel synthetic route was developed to prepare polyimide–nanocrystalline–titania hybrid optical films with a relatively high titania content (up to 50 wt %) and thickness (20–30 μm) from soluble polyimides containing hydroxyl groups. Two series of newly soluble polyimides were synthesized from the hydroxy‐substituted diamines with various commercial tetracarboxylic dianhydrides. The hydroxyl groups on the backbone of the polyimides could provide the organic–inorganic bonding and resulted in homogeneous hybrid solutions by controlling the mole ratio of titanium butoxide/hydroxyl group. AFM, SEM, TEM, and XRD results indicated the formation of well‐dispersed nanocrystalline‐titania. The flexible hybrid films could be successfully obtained and revealed relatively good surface planarity, thermal dimensional stability, tunable refractive index, and high optical transparency. A three‐layer antireflection coating based on the hybrid films was prepared and showed a reflectance of less than 0.5% in the visible range indicated its potential optical applications. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1433–1440, 2010     

Identification of metabolites of Danggui Buxue Tang in rat urine by liquid chromatography coupled with electrospray ionization time‐of‐flight mass spectrometry

A method coupling liquid chromatography with electrospray ionization time‐of‐flight mass spectrometry (LC/ESI‐TOF/MS) has been developed for rapid and sensitive analysis of rat urinary metabolite profile of Danggui Buxue Tang (DBT), a well‐known Chinese herbal formula. After oral administration of DBT, urine samples were collected during 0–24 h, and then pretreated by solid‐phase extraction. A total of 68 compounds including 13 parent compounds and 55 metabolites were detected in the drug‐containing urines compared with blank urines. The total analytical time was less than 20 min. Metabolites of DBT were identified using dynamic adjustment of the fragmentor voltage to produce structure‐relevant fragment ions. By using this approach, the mass accuracy of precursor and fragment ions was typically within ±5 ppm of the theoretical values, and enabled the identification of 43 metabolites including 27 isoflavanoid and 16 phthalide metabolites. Our results indicated that glucuronidation and sulfation were the major metabolic pathways of isoflavonoids, while glutathione conjugation, glucuronidation and sulfation were the main metabolic pathways of phthalides. No saponin‐related metabolites were detected. The results of the present study provided important structural information relating to the metabolism of DBT. Furthermore, this work demonstrated the potential of the LC/ESI‐TOF/MS approach for identification of metabolites from Chinese herbal medicines in urine. Copyright © 2009 John Wiley & Sons, Ltd.